[bitbake-devel] more pedantry involving the proper use of PREFERRED_PROVIDER_*

[Robert P. J. Day]

  and now, some picky questions about the use and processing of
PREFERRED_PROVIDER, once again using actual examples pulled from the
poky repository.

  first, is there anything magical about the use of the prefix
"virtual/" when defining and selecting providers? i'm well aware of
the most common usage of this -- "virtual/kernel". and there are other
good examples like "virtual/bootloader", "virtual/xserver" and so on.

  but there are other non-virtual definitions, such as:

  PREFERRED_PROVIDER_console-tools ?= "kbd"

so if i select "console-tools" to be incorporated into my eventual
image, that line will end up selecting the "kbd" recipe. so why are
some of these preferences using "virtual/" and some not? is it just a
philosophical choice? could i do something goofy like define and
select names like "rday/recipename" just as well?

  next, wouldn't the preferred provider for a recipe be, by default,
that same name? it seems odd to see something like:

  PREFERRED_PROVIDER_ltp ?= "ltp"

even if something else provides "ltp", isn't the above redundant? or
is there something subtle here i'm missing?

  finally, i found this simple example i want to use as a teaching
example involving make and remake. there's a definition for the "make"
recipe that looks perfectly normal, and there is also a recipe
definition for an alternative, remake, whose .bb file contains:

  PROVIDES += "make"

and whose remake.inc file includes:

  ALTERNATIVE_${PN} = "make"
  ALTERNATIVE_LINK_NAME[make] = "${bindir}/make"
  ALTERNATIVE_TARGET[make] = "${bindir}/remake"
  ALTERNATIVE_PRIORITY = "100"

so i'm assuming i could just do something like:

  PREFERRED_PROVIDER_make = "remake"

yes? is this explained anywhere in the yocto docs in more detail?
thanks.

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================